This invention relates to a new strain of Human Immunodeficiency Virus (HIV), which is the major etiological agent of Acquired Immune Deficiency Syndrome (AIDS). More particularly, this invention relates to the new strain, products derived from the new strain, a diagnostic method for detecting antibodies to the strain in biological fluids, and to a diagnostic kit for carrying out the method.
An important genetic polymorphism has been recognized for the human retrovirus at the origin of Acquired Immune Deficiency Syndrome (AIDS) and other diseases, such an Lymphadenopathy Syndrome (LAS), AIDS-related complex (ARC), and possibly some encephalopathies (for review see Weiss, 1984). Indeed many of the isolates analyzed have a distinct restriction map, even if recovered from the same place and time (Benn et al., 1985). Identical restriction maps have been observed for the first two isolates designated Lymphadenopathy-Associated Virus, LAV (Alizon et al., 1984) and Human T Cell Lymphotropic Virus Type 3, HTLV-3 (Hahn et al., 1984), and thus appear as an exception.
The genetic polymorphism of the AIDS virus was better assessed after the determination of the complete nucleotide sequence of LAV (Wain-Hobson et al., 1985), HTLV-3 (Ratner et al., 1985; Muesing et al., 1985), and of a third isolate designated AIDS-associated retrovirus, ARV 2 (Sanches Pescador et al., 1985). In particular it appeared that, besides the nucleic acid variations responsible for restriction map polymorphism, isolates could differ significantly at the protein level, especially in the envelope (up to 13% difference between ARV and LAV), by both amino acid substitutions and reciprocal insertion-deletion (Rabson and Martin, 1985).
Clinical and epidemiological studies have highlighted the presence and recent spread of AIDS and associated diseases in Central Africa (Piot et al., 1984; Van de Perre et al., 1984; Clumeck et al., 1984; Montaqnier, 1985). They have also revealed that transmission principally occurs through heterosexual contacts, unlike in the developed countries, and from mother to child. In fact, a much larger fraction of the population is exposed to AIDS than in the USA or Europe, hence the notion that AIDS is endemic to Central Africa. In spite of these epidemiological peculiarities, a retrovirus that is structurally and biologically indistinguishable from the European or American isolates and whose proteins are antigenically indistinguishable was found in patients and in healthy carriers originating from central Africa (Elrodt et al., 1984; Brun-Vezinet et al., 1984; Bailey et al., 1985).
Given the distant geographical origins of the retrovirus from African and U.S. patients, the significant differences in their respective isolates, and differences in modes of transmission, there exists a need in the art for information on genetic polymorphism of the virus. More particularly, there exists a need in the art to investigate the genetic variability of the AIDS virus, in particular its range, the underlying mechanisms, and the apparent existence of hypervariable or well conserved domains in the viral proteins Indeed, such conserved domains are likely to be associated with important biological functions, and their delineation would be a step towards understanding the molecular mechanisms of viral pathogenicity. Furthermore, identification of the retroviruses must be considered for the development of genetically engineered proteins for therapeutic purposes.